She was born in the darkness of the Alley. Her parents were both disfigured Morlocks hiding from the light of human society above. She too was a monster. Bones protruded from her skin as hideous reminders that she was a mutant. The young Morlock grew up in a world that hid from persecution, her fantasies were those of the surface world, where fortune, light and love awaited. During all this time she had never beheld beauty.

   Then came the X-Men. Callisto, leader of the Morlocks deemed the time right to chose a mate. She deemed it fitting that she take the most beautiful surface dweller as husband. She chose an Angel. Her henchmen kidnapped Warren Worthington the III aka Angel, and intended for him to marry Callisto. As a child Sarah gazed upon his pale visage and feathered wings and for the first time knew beauty. Soon after she beheld beauty a second time. Storm, leader of the X-Men, challenged Callisto to a duel and to the winner went leadership of the Morlocks. It was darkness versus light. Callisto was dark, Storm was light. Storm won and Callisto, saved from a fatal blow only by the Morlock Healer, gave her leadership of the Morlocks. Storm spoke of the surface and Sarah listened. Promises were made and the heart of the young Morlock was content.

   Then came the Marauders. Their fury swept through the Alley as they masacred as many Morlocks as they could find. To breach the Morlocks' defenses they had needed help. A thief known as Gambit had lead these murderers into the Alley but when he saw the horror he had unleashed he tried to stop them. Sabretooth beat him with contemptus ease. Knowing he could not save them all, Gambit opted instead to save one small girl with bones poking out of her skin.

   Then came Mikhail. The older brother of the X-Man Colossus deemed the remaining Morlocks unworthy to remain in this world. The X-Men watched helpless as Mikhail seemingly commited suicide and took the remaining Morlocks and Calisto with him. In actuality he banished them all to a new world. A harsh new world that made the dismal Morlock Tunnels look glamorous. Though they did not thrive, the Morlocks survived. As the first generation of Morlocks grew old, the younger generation, Sarah included, became dis-enchanted with their elders. They dismissed them as weaklings that stood by as they were slaughtered and shunned. The younger generation wanted revenge for the harms that had been committed against them.

   Sarah took the name Marrow and became leader of Gene Nation, a terrorist group seeking revenge on humans. Their first action was to slaughter all the humans they found in a NY nightclub. These human's crimes had been decadence, luxury and indulgence, while the Morlocks had been cast from this uplander society. After this she kidnapped Emma Frost to use to get the attention of the first one, creator of the Morlocks: The Dark Beast. Emma defeated them, and might have killed Marrow if not for the Dark Beast's intervention in the form of an explosion. Other members of her group combated various X-Men at different times.

   On the aniversery eve of the Morlock masacre, Marrow and Gene Nation kidnapped an amount of humans tantamount to the number of Morlocks that had died at the hands of the Marauders. They intended to kill them all on the aniversery. Calisto and Colossus contacted the X-Men, and with the help of Storm and Wolverine went to put a stop to the killing. In the end, Marrow found herself in single combat against Storm. The duel was fought, and to save the lives of all the innocents, Storm ripped Marrow's heart from her chest...

   ...but Marrow did not die. Unknown to Storm, Marrow's mutation not only gave created an excess of bones, but she was also born with two hearts. When Operation: Zero Tolerance declared its war on mutants, Marrow along with Calisto, attacked Peter Henry Gyrich, Zero Tolerance's government contact. Although Spiderman stopped them from killing Gyrich, Calisto was sorely wounded. The two returned to the sewers and it was there that Calisto pleaded with Marrow to seek out the X-Men and fight the peaceful battle instead of the bloody one. Marrow encountered Iceman and Dr. Reyes in New York and helped them to battle Bastion. When Bastion was defeated the three returned to the X-Mansion. Iceman asked Marrow to live with them, and for the time being she accepted.

   Storm was not at all pleased to hear that Marrow had been invited to live there, and many other X-Men expressed there open scorn. Cannonball and Marrow seem to be forming and attraction while Marrow views Angel as a god. Now that Storm and Wolverine are in charge of the school, Marrow will be faced with less leniancy and more trials in the future to come...